A substance functioning as a high-performance material is called a “performance substance” in the present invention. Performance materials are known which contain a performance substance dispersed in a dispersion material. Known performance substances include pesticides such as herbicides, and insecticides; medicines such as anticancer agents, antiallergic agents, and antiphlogistic agents; and colorants.
On the other hand, the digital printing techniques, which are typified by electrophotographic techniques and inkjet techniques, are becoming more and more important for image formation in offices and families. In particular, the digital printing techniques employing a colorant-containing composition are progressing remarkably rapidly in recent years.
The inkjet method, as a direct recording method, has advantages of compactness and low power consumption of the apparatus. The inkjet techniques are progressing rapidly in image quality by use of finer nozzles and other improvement. In an inkjet system, the ink supplied from an ink tank is heated in a nozzle by a heater to be ejected by bubbling and evaporation onto a recording medium to form an image. In another inkjet system, an ink is ejected through a nozzle by vibration of a piezo element.
In the inkjet printing, use of a pigment-dispersion ink is investigated for improvement of image weatherability and ink fixability. Use of a nano-particulate metal is also investigated: Japanese Patent Application Laid-Open No. H11-76800, for example, discloses use of a dispersion of colored nano-particulate noble metal as a paint.
Use of the inkjet technique is investigated for formation of an electroconductive organic thin film as shown, for example, in Japanese Patent Application Laid-Open No. 2000-33712.
The above-disclosed techniques need to be improved further for more excellent colorant in inkjet composition, more stable image formation with a specific composition, and more stable pattern formation.
Meanwhile, a semiconductor circuit substrate or a print wiring plate to be mounted on an information terminal is produced by any of the known processes below:
(1) Formation of a copper wiring pattern through steps of coating a copper-plated lamination plate with a resist, exposing the resist to a circuit-patterned light by photolithography, removing of non-exposed portion of the resist by dissolution, and etching of the resist-removed portion;(2) Formation of an electroconductive pattern through steps of printing an intended pattern of an electroconductive paste on a ceramic substrate by screen printing, and sintering the metal fine particles in the electroconductive paste by heat treatment in a non-oxidative atmosphere;(3) Formation of a copper wiring pattern through steps of vapor-depositing an electroconductive metal in a thin film layer, coating the electroconductive layer with a resist, exposing the resist to circuit-patterned light by photolithography, removing of non-exposed portion by dissolution, and etching the resist-removed portion.
With the remarkable trend to miniaturization of information terminals in recent years, the circuits of semiconductor mounted on the information terminals are coming to be miniaturized and the wiring pitches of the print wiring are made smaller. With the decrease of the minimum line breadth of the circuit pattern on the printed-wiring plate, the pattern layer thickness is also decreased. However, the process using a copper-plated lamination plate or the process by screen printing has disadvantages that a fine pattern formation is difficult, waste liquid treatment is necessary, and installation cost and production cost are high, whereas the process of the vapor deposition and etching has disadvantages that waste liquid treatment is necessary, and installation cost and production cost are high.
For canceling the above disadvantages, use of an inkjet system is investigated. For example, a wiring pattern is printed on a substrate by an inkjet system with a fine-metal particle ink containing a fine particulate metal of an average particle diameter of not larger than 100 nm dispersed in water or an organic solvent, and the printed substrate is treated by heating or light irradiation to decompose and vaporize a polymer or surfactant contained in the wiring pattern to obtain an electroconductive pattern of a prescribed film thickness (Japanese Patent Application Laid-Open No. 2002-134878). This process needs to be improved further for higher wiring density with uniformity of wiring pattern line breadth without short circuit between adjacent wiring lines; preferably with sharpening of the wiring pattern edge to prevent the short circuit.